The rapid transformation of battery-operated electric vehicles leads to the piling up of dead batteries after use. Finding a green and efficient way to recycle these batteries containing essential metals is crucial. Hence, the present work proposes a rapid, facile, and benign synthesis of NiMnCo-oxalate from spent lithium-ion batteries that are then directly used as electrodes for supercapacitors. NiMnCo-oxalate was extracted from dead batteries using citric acid as green leachate. Microwave irradiation was employed to expedite the process of leaching. Microwave-irradiated citric acid-assisted NiMnCo-oxalate when tested for supercapacitor showed a high specific capacity of 93 mAh g-1(560 F g-1) at 1 A g-1. The designed asymmetric supercapacitor showed good capacitance retention with an energy and power density of 36 Wh kg-1and 118 W kg-1, respectively. Further, a polyaniline (PANI)//tungsten oxide (WO3)-based electrochromic device was powered by the asymmetric supercapacitor indicating the successful application of recycled materials for similar applications. © 2022 American Chemical Society. All rights reserved.